A completely dust-free clean mixing technology for lithium battery powder active materials, and the corresponding intellectual property protection layout. The lithium battery active material of the powder is packaged by using the corresponding dissolvable packaging bag during the process of mixing the lithium battery powder active material (the outer bag of the packaging bag is still a traditional aluminum plastic film packaging bag, and the inner bag is soluble) The packaging bag) puts the dissolvable packaging bag and the lithium battery powder active material into the solvent used in the pulping process, thereby achieving the process of cleaning and pulping, completely avoiding dust pollution.
In order to promote the progress of the electrochemical reaction and reduce the resistance of the electrode reaction, most lithium battery active materials use a powder material, including a positive electrode material, a negative electrode material, a binder material, and a conductive material of a lithium battery. The active material of the lithium battery must be compounded, mixed with a corresponding solvent (for example, NMP or water), stirred and dispersed (or dissolved) uniformly, and formed into a slurry to be used for the manufacture of a lithium battery.
In the process of mixing, the small particles in the active material of the powder are easy to form dust pollution and soil the working environment. It is also easy to soil the working environment by filling the active material with a small amount of powder remaining in the packaging bag. The lithium iron phosphate cathode material and the carbon nanotube conductive agent are representative, and the dust pollution is particularly serious.
To this end, the author developed a completely dust-free clean mixing technology for lithium battery powder active materials, and carried out the corresponding intellectual property protection layout. The lithium battery active material of the powder is packaged by using the corresponding dissolvable packaging bag during the process of mixing the lithium battery powder active material (the outer bag of the packaging bag is still a traditional aluminum plastic film packaging bag, and the inner bag is soluble) The packaging bag) puts the dissolvable packaging bag and the lithium battery powder active material into the solvent used in the pulping process, thereby achieving the process of cleaning and pulping, completely avoiding dust pollution.
According to the PVDF bag, the bag with a size of 350mm x 460mm has a thickness of 40 microns, a weight of 21.76g and a volume of 8 liters. Such a bag was dissolved in NMP at room temperature for 5 minutes. For the lithium iron phosphate material, it can be loaded with about 6 kg, so the weight ratio of the bag to lithium iron phosphate is 21.76/6000 = 0.36%. The amount of PVDF added in the lithium iron phosphate positive electrode formulation is 2.5% relative to the positive electrode, which means that the PVDF bag is 14.4% relative to the entire PVDF adhesive, and there is no significant change or influence on the entire bonding effect. Impurities, because PVDF bags and adhesives are made of PVDF. Even if the amount of PVDF binder in the formulation is reduced to 1.5% relative to the lithium iron phosphate anode, the PVDF bag is only 24% relative to the total PVDF binder. This soluble bag is just a simple film that prevents powder leakage. In the actual production, the main packaging strength is provided by the aluminum plastic film packaging outer bag, which has a thin soluble PVDF packaging bag.
For ternary NCA and NCM materials, a PVDF bag with a size of 350mm x 460mm and a thickness of 80 microns is required. The weight is 43.52g and the volume is 8 liters. It can hold about 17 kg of NCA and NCM cathode materials. Such a bag was dissolved in NMP at room temperature for 5 minutes. The weight ratio of the bag relative to the positive PVDF was 43.52 / 17000 = 0.26%. The amount of PVDF added in the positive electrode formula of the ternary material is 1.5% relative to the positive electrode, which means that the PVDF bag is 17.3% relative to the entire PVDF adhesive, which has no obvious influence on the whole bonding effect and will not bring Impurities, because PVDF bags are made of PVDF. Even if the amount of PVDF binder is reduced to 1.0% relative to the positive electrode in the formulation, the PVDF bag is only 26% relative to the entire PVDF adhesive.
At present, the immediate change is that the conductive agent is treated with a soluble PVDF packaging process—conductive carbon black (SP of Temco), conductive graphite (KS-6 of Temco), carbon nanotubes and PVDF. The adhesive itself. The impact of these materials, PVDF bags, is completely negligible. For the feeding of the conductive agent SP, the dust is very serious, and the technology of the soluble packaging bag is urgently needed to improve the operating environment of the feeding. This effect is immediate and has no side effects. Conductive carbon black SP sold several thousand tons in the domestic market last year. Such a technique is also applicable to the negative electrode material, and the material of the packaging bag is preferably a water-soluble polymer material.
The benefits of doing this are:
1. Completely avoid dust pollution during the process of using lithium battery powder active materials;
2, can be quickly charged;
3, easy to achieve automation;
4. No complicated ton bag feeding and air conveying technology is needed, saving investment and cost of feeding equipment, and no need for post-maintenance feeding equipment;
5, no need for secondary weighing measurement, can be accurately weighted;
6. Avoid sensitive battery materials (such as NCA) from contacting the water and dust in the air, avoiding air pollution during the feeding process, pollution caused by the conveying machinery, and pollution caused by the wear of the conveying equipment;
7. Protect workers' health and completely eliminate dust hazards;
8, the production of high-quality batteries requires a highly clean environment, absolute dust-free pollution is a must for advanced battery companies.
In 2016, the output of China's domestic lithium battery cathode materials was 161,600 tons, an increase of 43% year-on-year, and the output value exceeded 20 billion yuan. In 2016, the domestic output of anode materials was 122,500 tons, a year-on-year increase of 68.27%. In 2016, the output value of anode materials was 6.639 billion yuan, a year-on-year increase of 64%. Calculated in a common 25-kg bag, China needs 6.46 million such bags per year in the cathode material industry; 4.9 million such bags are needed in the anode material industry each year; and the adhesive and conductive industries also need this. The soluble packaging bag is a dust-free mixing process. A technical solution for the cleaning and mixing process through a dissolvable package, providing such a solution to a large lithium battery plant, with additional technical fees, is feasible.
The entire battery industry related materials will increase several times in the future, and the demand for such dust-free mixing process solutions will also increase several times. All lithium battery plants are suitable for such technology and are not exclusive. The corresponding intellectual property protection layout has been carried out, and there is no vicious competition. The author hopes that such a dust-free mixing process solution can contribute a small amount of power to the large-scale, automation and humanization of lithium battery production in China.
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